Nuclear substituted triarylmethane derivatives and process of making them



Patented July 27, 1943 .aszsmss Nwenmm ermerrrurun TRIARYLMETH- I sunnnmvmms AND rnoosssor MAK- INGTHEM Lyman Challil'ey, Brick ll iownship, GB'ca-fifihunty,

No Drawing.

Application'lfie'cerfibcr I3, 193 9, Serial No. 309,107

:5 Clai'ms. (01.26%387) This invention relates to improvements in jetfecting nuclear substitution in the colorless derivatives of triarylmethane dyes, and to the novel substituted cornpouhdspso produced. carrying out such'reactidns, important to maintainthe stability of the colorless derivative and to carry out the substitution reaction under conditions which will-retard or prevent the conversion of the colorless derivative into the parent dye.

In the past such nuclear substituted compounds have been prepared largely by condensation of substituted aryl amines and aldehydes, or their equivalent, to form triarylmethane derivatives; or by substitution in the amino triarylmethane dyestuffs.

The preparation of substitution products by condensation of the substituted aryl amines or aldehydes is limitedin its application by the conditions required for condensation, which will:

split oil or-change sensitive groups, such as merairy; and by the course of the condensation reaction, which in presence of nuclear .substituents in the and amine, .or aldehyde, may proceed in undesired or unexpected directions.

The iireparatiori of substitution products by substitution in the amino teriaylmethane dyestu'fls is limited by the great chemical activity of these dyes, which aresub'ject to oxidation, .reduc'tlon, and less Well defined forms of decomposit'ion. As a result, the preparation of identifiable nuclear substitution products from the amino triarylmetnane dyes has been confined largely to sulfonation reactions, which can often be carried out satisfactorily with the dyes.

Thus, in the past there has been no general broadly applicable method for the preparationof nuclear substituted triarylmethane derivatives. The" lack of such a process has prevented the preparation of certain useful compounds of this type. example is tnatof mercury derivatives, which WhitmoreJaIid Leuc'k reported "were not obtained in an exhaustive research on "the .subject. 7 Their paper'in the Journal of the American Chemical Society, volume 51, September, 1-1929, states 'on page 2783 under the caption, 'Attempted 'rner'curation of malachite green and its base',. that This substance was treated with mercuric acetate under a great variety --of =conditlons. The solvents used included various concentrations' of. ethyl alcohol, acetic acid, ethyl acetate, benzene, and mixtures of'thes'e. The time of heating'vari'ed from a few minutes to ten days. In no case was there any evidence of the formation of organic mercury compounds? An object or my invention. :is to provide a broadly amilic'able' general method for the preparation' of nuclear substituted compounds from di and 'tr'i-amin'o 'tflarylmethane derivatives. These compounds have use as antioxidants, as dyestuffs, as pharmaceuticals, etc. By means of my invention it is possible to introduce directly as nuclear substituents not only the more usual types, such as chlorine, bromine, 'm'tro, but also the moresensitivetypes, such as mercury.

Thebasis'of my "invention is my discovery that the colorless derivatives of theam'ino triarylmethane 'dyes readily undergo smooth and controllab'le nuclear substitution provided the reaction is carried out under conditions which'permit substitution to take place without the formation of dye, or before therehas beenen-ough dye formationto result in'gross decomposition. Q

En order to make the-detailed discussionof this reaction more intelligible '1' shall first explain what I mean by colorless derivatives of the ammo *triarylmethan'e dyes.

Doebner's'Vlolet'and'pararosaniline may be 'cons'idere'd prototypes of the amino triarylrnethane dyes. These areggenerally formulated as'followsz Doebners Violet Pararosaniline ITTHQ NH2 17TH: lT Hz ITIH:

Colorless derivative of Colorless derivative of Doebncrs Violet pararosaniline Here Y is the negative radicle added to the methane carbon atom. Corresponding to differences in Y, a considerable number of types of these colorless derivatives are known. Thus, for

examples, the carbinol type, or dye base, has for Y the hydroXyl group, OH; the ethers have for Y such groups as methoxyl, OCH3, ethoxyl, -OC2H5; benzoxyl, OCH2CSH5; the nitriles have for Y the cyano group, CN; etc.

These colorless derivatives may be prepared from the dyes by known methods using suitable reagents. Suitable reagents are the alkali metal salts MY, where M is an alkali metal ion, and Y the above-mentioned negative radicle. For example, the carbinols may be prepared with alkalies, the others with sodium alccholates, the nitriles with alkali cyanides, etc. I

The colorless derivatives may also be reconverted into the dyes by suitable reagents and methods. The majority of the known types of colorless derivatives are converted into the dyes by acids alone. Examples are the others, the amine bases, the carbthiols, the carbinols. This conversion takes place so readily that the dyes are generally considered simply as salts of the carbinols. Fo example, in the standard enderivatives of triphenyl methane dyes are given,

by way of example, these including the cyanide, the carbinol, the amine base and the sulfite.

Therefore, the negative radicles represented by Y include the hydroxy group -'OH, the ether group OR, the nitrile group CN, the amid group NH2, the sulfhydrile group SH, and the sulfite group SOsH.

Likewise, because of the ease of conversion of such colorless derivatives into the dyes, it has generally been a matter of indifference whether the dye or some colorless derivative, usually the carbinol, were used as the starting product in a reactioninvolving an acidsoluticn. For illustration, German Patent No. 6.714 gives examples for the sulfonation of malachite green in which either the carbinol or the dyestufi is used as the starting product. The claim properly reads on the dye because the sulfuric acid used in sulfonation converts the carbinol into the dye, and the solution of the carbinol in sulfuric acid is a solution not of the carbinol but of the dye. Similarly, in German Patent No. 27,275 directions call for a solution of 25 kg. of malachite green carbinol in -0 liters of water and'50 kg. of acetic acid. Actually this amount of malachite green carbinol is not soluble unchanged in this amount and concentration of acetic acid. Solution takes place only on conversion of the carbinol into the dye, and the solution is one of dye, not of carbinol, as can readily be determined by col0ri metric comparison with dye solutions of known composition.

It has long been believed that the conversion of a colorless derivative into a dye involved something more of a structural change than simple salt formation. This belief has found expression in the structural formulas given above for the dyes and their colorless derivatives, and the mechanism of the change is formulated as follows, using malachite green as an example:

Malachite green carbinol Mono-hydrochloride of malachite green carbinol (amine salt) Malachite green chloride (dye) Thus, the first product of the reaction of the colorless derivative with acid is not a dye but an amine salt, which-is unstable and passes into the dye on loss of water.

In spite of these long known differences between the colorless derivatives and the corresponding dyes, the practice has been to consider the two types of compounds equivalent in their synthetic reactions, the acidity or alkalinity of the reaction mixture determining whether the compound was present as dye or as colorless derivative.

The reactions generally used to introduce substituents into aryl amines involve acid reaction mixtures. The acid is present either as an initial constituent of the mixture or is formed in the reaction. Therefore, in the past when colorless derivatives of the basic triarylmethane dyes have been used as starting products in'reactions which might produce substitution, they have reacted as dyes because they were in fact in the dye form in the acid reaction mixtures.

Now I have discovered that the chemical properties of the colorless derivatives are distinctly different from those of the dyes as regards behavior on substitution. Whereas the dyes suffer severe decomposition when treated with many of the reagents which produce substitution, the colorless derivatives substitute smoothly and without undue decomposition.

My invention consists essentially in carrying out substitution in the colorless derivatives of' basic triarylmethane dyes under conditions which hold the major part of the triarylmethane compound stable in the form of the Colorless cc. of a. normal solution of sodium cyanide in 65% methyl alcohol. The clear colorless solution is treated immediately with 1 volume (130 cc.) of water, whereupon the dic'yanomercuri malachite green carbinol precipitates. This has the probable structural formula:

3,3 dicyanomercuri-i,4-bis-dimethylamino-triphcnylcarbinol The solid is collected after 6 hours in which to settle, washed thoroughly with water and dried in a desiccator.

This dicyanomercuri derivative forms a crystalline compound from toluene. Pure toluene and the mercury compound in the proportion of to cc. of toluene to 1 g. of mercury compound are stirred vigorously together at room temperature for not longer than four minutes. The resulting solution is decanted from any residue. Colorless crystals begin to separate in a few minutes. The mixture is allowed to stand for 4 days, the crystals are collected, washed with toluene and air dried. The crystals are less soluble in both alcohol and toluene than the original compound. Put in a cold melting point bath and heated the compound decomposes above 200 C., the temperature of rapid decomposition varying with the rate of heating.

Other salts, such as the acetate, chloride, sulfate, thiocyanate, etc., of the organic mercury compound are readily prepared from the hydroxide without changing the carbinol structure. These salts all have the general formula:

where X is the anion of the acid used.

The chloride and thiocyanate are relatively insoluble in alcohol and may be prepared by precipitation from an alcoholic solution of the acetate by treatment with an alcoholic solution of calcium chloride or potassium thiocyanate. The sulfate, acetate, and other soluble salts may be isolated by solution of the dihydroxymercuri compound in alcohol containing 2 equivalents of the proper acid followed by precipitation through the addition of 1 to 2 volumes of water.

In the substitution reaction described in this example dye formation is retarded by use of the nonionizing solvent ethyl acetate and reduction in the acid concentration of the reaction mixture below that commonly used in the mercuration of aryl amines. A little dye is formed, but the quantity is too small to result in any considerable decomposition or materially reduced yields.

The preparation of dye from this mercurated carbinol is illustrated in the three following examples.

EXAMPLE 1A.Preparaticm of the dye acetate- One g. of dihydroxymercuri-bis-dimethylaminotriphenylcarbinol is dissolved in 12 cc. of methyl alcohol containing 2 by volume of acetic acid,

- than from the solid dye.

and the solution boiled under a reflux condenser for 20 minutes. The solution is then cooled, diluted with 2 volumes (24 cc.) of water and allowed to stand 24 hours. It is then filtered from any diacetoxymercuri-bis-dimethylaminotriphenylcarbinol which may not have been converted into dye. The deep blue filtrate contains in solution diacetoxymercuri-malachite green acetate, having the probable structural formula:

3,3'-diacetoxymercuri-malacliite green acetate This dyestufi is quite soluble in alcohol and in water. Itmay be isolated by evaporation of its aqueous-alcoholic solution, but is inclined to be gummy or tarry. In general it is better to prepare the dye solutions from the carbinol rather This dyestuif dyes silk and wool to a color indistinguishable to the naked eye from dyeing with unmercurated malachite green.

When the aqueous-alcoholic solution of this dye is treated with sodium chloride, even in small amount, a precipitate is obtained. This precipitate contains only a small proportion of the dichloromercuri malachite green chloride, which might be expected, and consists mainly of dichloromercuri malachite green carbinol. Analysis of a representative precipitate produced by sodium chloride shows 9.3% chlorine. The calculated percentage of chlorine in dichloromercuri malachite green chloride is 12.7%, and in dichloromercuri malachite green carbinol is 8.7%

EXAMPLE 1B.-Preparation of the dye benzenesuZfonate.--One g. of dihydroxymercuri malachite green carbinol is dissolved in a mixture of 3.45 cc. of normal aqueous benzenesulfonic acid solution and 35 cc. of methyl alcohol. The solution is heated to boiling. It should then give no immediate precipitate on dilution with water. The deeply colored solution contains the benzene sulfonate of the dimercuri malachite green, having This dye is soluble in alcohol and in water. It may be isolated by evaporation of the solvent, but is obtained in a tarry form. The dyestuff may be partially salted out of solution along With sodium sulfate by treatment of the alcoholic solution prepared as described above with 2 volumes of /2 molar sodium sulfate solution. The dye solution gives an insoluble precipitate with sodium chloride. The dye solution dyes silk the same color as unmercurated malachite green.

EXAMPLE 1C.-Preparation of dicyanomercuri malachite green benzenesulfonate.--One g. of dicyanomercuri malachite green carbinol as precipitated from alcohol by water (not the toluene compound, which is less soluble) is dissolved in 6 d ter. meth l al ghet. eq e t:- 9 fle treated witha mix u e-9f 9-. 2 Qi; n mal reetsee: zen su i n c aci and 6. i filp -r Th l nch-is mired e lt encw m d:Shu a l d-12 ms, and allow d testand at r mr em atn fer-24: hours The smuti npente ne. lQllBQlf curl malachite reen. benzenesu-l qp te aYil the probab e.stru turalfnr ula GEN-Hg:-

3,3 dicyanornercuni-malachiteegreen ben-zene-sul fonate This dye is readily soluble in alcohol and in mixtures of alcohol and water, but is not very soluble in pure water. This dyestufi dyes silk andwool toacolcr indistinguishable to naked eye from dyeing with unmercurated malachite green. ltmay be'isolated by eyaporation oi its alcoholic solution, and is tarry :wheniso. obtained. Sodium chloride in low concentration produces no precipitate inthe aqueousor .aqueousealcoholic derivatives of the general type,

. 'QIQ'." 'Nwnm More);

7 i l l X Hg O are readily obtained. Here X, X and X are anions, but not necessarily all the same anions.

EXAMPLE ,Z-T Q V Q n J th et y e he d rive 1mm mlq it ti to th .d m etbl rie mpouhd'.-A solution of-3'A g. mole) of, 414' bis-dimethylamino-triphenylmethyl-ethylether in 200 cc. of warm ethyl acetate is treated with 6.4

g. @i molefof 98% mercuric acetate in solid form, without addition of acetic acid and the mixture boiled under a reflux condenser with vigorous stirring for 15 minutes. The light blue solution is then cooled, filtered from .the'precipitated mercurous acet ate-, .sha ken with an added 5 cc. of 4 normal aqueous potassium hydroxide solution and the ethyl acetate allowed to evaporate 111th :,air.at roqrn temperature. The gummy residue is separated from the aqueous layer which remains after the evaporation of ethyl acetate, and washed with water. The residue is then taken up in 70 cc. of absolute methyl alcohol at room temperature, the solution filtered, and the filter washed with cc. more of alcohol, which is added to the filtrate. The filtrate is treated with 15 cc. of 2 normal potassium hydroxide solution in methyl alcohol. There immediately forms a precipitate of the dimercuri This precipitate is allowed to settle for 1 hour,

then collected on a filter, washed with a little cold alcohol,- then thoroughly with water, and dried in a vacuum desiccator. The substance contains 45.5% mercury and is duite pure enough for most uses.

For further purification, 1 g. of the substance is suspended in 12 Co. or absolute methyl alcohol, th mixtyre oo ed trio and treated with 2 cc. of 'ahdld normal solution'of acetic acid in 95% m ta fliPq-l W i h s added lpwly wi t 1 U T merdury ioi noilnd g es.- nt e ti he .c xvme turb t ime h m e ri- 3 hen l i l-fihfl hl- 1 S e m filt r d,

and the" hydroxymercuri compound reprecipitatedby addition of 2 cc. of 2 normal pdtassium hydroxide solution in methyl alcohol. The pre t oiougl'gly with water desiccator over sulfuri on't "{i6.5% mercury,

pul'es of methyl alt ce dec omposes when heated above 29 9?, the temperature "at. which decomposition nlgfvjvitn the rate 1 time the samplefis tjme m g qihtbath. The other is readily converted into the mercurated dyestufiby the same processes which n have been described for the conversion of the mercurated; carbinol into the dye. The ethyl group is hydrolyzed by acid and the same dyes are formed" 'asiwhen the: mercurated carbinol is used as the starting product.

In this substitution reaction of the ethyl ether derived from malachite green which I have described there is virtually no formation of dye. The" ether in ethyl acetate solution is practically insensitive t'o the small quantitiesof acetic acid formed even though a larger proportion of mercuric acetat'eto colorless dye derivative is used than-ihthe examplewithlthe carbinol.

ExAmmlniiiMercuration of'the nitrile derived from malachite green to form the dimercuri compoun -a solution Ora-r g. (2/ mole) of 4,4 bis dimethylamino triphenylacetonitrile in .150 cc. of warm ethyl'aceta'te'a'nd .3 cc. of acetic acid istreatedlwith 12.8 g. 5 mole)' of 98% mercuric acetate, and boiled in the absence of ultra violet light under a refiux' fcondenser for 1 /2 hours. The solution is then cooled, filtered from the precipitated r'nercurous acetate, and evaporated in vacuo from a ;30 C. bath to a volume of cc. The solution is filtered from the slight, newly formed precipitate, .the precipitate Washed with a little ethyl acetate which is added to the absolute methyl alcohol. The resulting solution is treated with 60 cc. of 2 normal potassium hydroxide solution in methyl alcohol. A precipitate forms, which is collected after 4 hours,

washed with a little methyl alcohol, and thorfiltrate, and the filtrate diluted with cc. of

oughly with water, and dried. The substance is purified by solution of 4 grams in 100 cc. of absolute methyl alcohol containing 1 cc. of acetic acid, filtration of this solution and reprecipitation of the mercury compound with 16 cc. of 2 normal potassium hydroxide solution in methyl alcohol. The precipitate is collected, washed with alcohol, then thoroughly with water, and dried in a vacuum desiccator over sulfuric acid. It contains 50.2% of mercury and has the following probable structural formula:

o JEN 3,23 dihydroxymercu1'i-4,-l'-bis-dimethylamino-triphenylacetonitrile This compound decomposes on heating above 200 C., the temperature of rapid decomposition varying with the rate of heating and'the time the sample is held at a high temperature in the melting point; bath.

EXAMPLE 3A.Conversion of the mercurated nitrile into the dye.-A solution of l g. of the dihydroxymercuri-nitrile described above in 100 cc. of 95% methyl alcohol and 2 cc. of acetic acid is exposed to the light of an ultra violet carbon arc. The solution is held in a quartz flask, and is stirred while the flask is cooled with water during the exposure. After 6 hours of exposure the solution is poured into one volume of water, allowed to stand 24 hours for precipitation of unchanged nitrile, and filtered through a finefilter paper. The deep blue filtrat contains a dye having the probable structural formula:

( l f ah V N-0I-0H= N(CH3)2 H 0 r 0 CH:( --OHg H THgGEN 3 acetoxymercuri-{i cyanomercuri-malacliitegreen acetate It should also be understood that while the invention has been illustrated by a number of specific examples, the invention is not limited to the precise procedures and chemicals mentioned in these examples, but may be carried out in other ways.

I claim as my invention:

1. A process for the preparation of substitution products from the colorless derivatives of triarylmethane dyes, of the type having the formula: V

where R is selected from the group consisting of hydrogen, an amino group, A is an amino group, and Y is a negative radicle selected from the group consisting of OH, OR' (R being alkyl), --CN, --NH2, SH,- -SO3H; consisting in effecting nuclearsubstitution in at least one of the aryl rings, by treating such colorless derivatives with an ionizable mercuric compound in the presence of a solvent.

2. As a new product, a substituted product of a colorless derivative of a triphenyl methane dye, such colorless derivative being characterized by having a negative radicle on the methane carbon atom, such substituted product having the foris a negative radicle selected from the group consisting of 0H, OR (R being alkyl) CN, NH2, SH, -SO:H.

3. As' a new product, diacetoxymercuridimethylaminotriphenylcarbinol, having the formula:

N(CHa)z N(CH3)2 Kc.Hg O Ollglc (5H 4. As a new product, dicyanomercuri-bis-dimethyl-aminotriphenyl carbinol, having the formula:

| among-Q Q UHCEN 5. 'As a new product, 3,3 dihydroxymercuri- 4,4-bis-dimethylamino-triphenylcarbinol, having the formula 

